Recommendations for the prevention of secondary Haemophilus influenzae type b (Hib) disease.

Haemophilus influenzae serotype b (Hib) can cause severe life threatening disease in healthy individuals, with over 80% of cases in the pre-vaccine era occurring in children under five years of age. The introduction of Hib conjugate vaccine into routine childhood immunisation programmes has resulted in a dramatic reduction in the incidence of invasive Hib disease across all age groups. The objective of this paper is to update existing UK guidelines on the prevention of Hib disease among contacts of an index case by reviewing the original literature and the current epidemiology of Hib carriage and invasive disease. Household contacts of individuals who develop invasive Hib disease are at higher risk of developing secondary Hib infection themselves, particularly if the contact is a young child or is immunosuppressed. Pre-school contacts of young children with invasive Hib disease are also at higher risk of developing secondary Hib infection. Rifampicin at a dose of 20mg/kg/day for 4 days is highly effective in eradicating pharyngeal carriage of Hib and reducing the risk of invasive Hib disease among household and pre-school contacts. Children under 10 years of age who develop invasive Hib disease should also receive rifampicin chemoprophylaxis to eliminate carriage and have Hib antibody levels tested around four weeks after infection. Hib vaccine failure cases should additionally have immunoglobulin concentrations measured and be assessed for evidence of an immune deficiency. If there is a vulnerable individual (child younger than 10 years or an immunosuppressed or asplenic individual of any age) among the household contacts of a case, all members of that household, including the index case, should receive chemoprophylaxis. All children younger than 10 years in the household should be appropriately vaccinated against Hib. Where more than one case occurs in a pre-school or primary school setting, chemoprophylaxis should be offered to all room contacts (including staff), and unimmunised and partially immunised children younger than 10 years should complete their primary immunisations, including a booster dose, as soon as possible. Families of children attending the same pre-school or primary school as an index case should be advised to seek medical advice if their child becomes unwell.